Tim's first link has a lot of info on the Stovebolt Engine.
If you only search "Stovebolt" in Wikipedia, it's only three lines (but each with a link of its own ... one going to the engine). There's a picture of the bolt in the first link in that page.
The terminology and the slang usage of Stovebolt refers to three different things:
A bolt (fastener) with a slotted head, used in the assembly of wood-burning stoves constructed from sheet metal.
The Chevrolet Stovebolt engine, so called because the valve cover, lifter cover and timing cover, utilizes a fastener that resembles a stovebolt.
A nickname for the Chevrolet Advance Design pickup trucks.Many many years ago [when Bill LePage (RIP) was still with us], the Stovebolt Page was actually listed in the Wikipedia page, along with some of the crazy terms John had in the FAQ page. It was fun ... while it lasted. Should have printed that out.
